Experimental investigation on the start-up and thermal performance of nanofluid-based pulsating heat pipe

The increasing demand of efficient heat dissipation especially for high heat flux and is essential due to the rapid development of microelectronics. Pulsating heat pipe with simple structure, fast response and excellent heat transfer performance plays an important role in this area of thermal management. In this study, a three-turns pulsating heat pipe using nanofluids of PbS/H₂O, Au/H₂O, Graphene/H₂O is investigated experimentally. The flow pattern is described and the thermal behavior of nanofluid-based pulsating heat pipe is compared with deionized water. Then, main factors affecting the heat transfer performance are studied comprehensively. Results show that pulsating heat pipe using nanofluids exhibits superior start-up characteristics and heat transfer performance compared to deionized water. The addition of nanoparticles facilitates the phase transition within the pulsating heat pipe, which increasing both the transient velocity and driving force of oscillatory motion, thereby improving the heat transfer efficiency. Furthermore, Graphene/H₂O presents the highest heat transfer performance among three nonfluids and the maximum is achieved at concentration of 1.0 wt%, filling ratio of 80% and tilt angle of 60°. The most inefficient process is located at the heat transfer from condensation to the environment, highlighting the improvement of cooling conditions for nanofluid-based pulsating heat pipe.